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Member Thingy
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Discussion Starter · #1 · (Edited)
I have always wanted to know how my car would stack up against other cars in terms of performance, so I recently wrote an algorithm which takes into account a car's specifications to calculate an overall performance rating. It takes into account things such as tire size, power, weight distribution, powerband, etc. etc. to assign a vehicle an overal number which can then be compared to other cars. It is very difficult to make numerical data coorelate, and so I began with data which is common to all cars, simple measurements which can be easily found around the internet or in a car magazine.

Keep in mind this equation uses specifications and data about a vehicle only to give a good INDICATION of a car's performance. It is by no means, absolute. The equation assumes maximum performance of the car in dry conditions on asphalt, with a perfect driver around a tight roadcourse. The overall ranking represents the order in which the cars fall from fastest to slowest lap time. THIS IS NOT A DRAG CALCULATOR, it is an overall performance calculator, with abiltity to put power to the pavement, useable powerband, and ability to turn weighed heavily. This said, there are 80+ cars I was able to collect data for in this excel sheet, and they are ranked accordingly. There is room at the bottom to add in your own car, or other cars which I did not include.

You can play around with the stats of the car, and change things like suspension or tire size or even do engine swaps and see how that would affect the car's overall performance.

Finally, there are many variables present, remember if you are changing one figure like ride height, or simulating weight reduction, remember to adjust things like stopping distance which would be affected by those. I wish I could have made the formula automatically adjust for this, but there is no standard for comparison of such things, and so it cannot be accurately written into the equation. It must be done manually.

Here it is: When you open it in Excel, it will ask if you want to enable macros, YOU WANT TO ENABLE MACROS WHEN PROMPTED. When you change stats simply click on either of the "update" buttons and it will recalculate the whole spreadsheet.

It can be opened here in another browser window, or downloaded and saved:

http://oregonstate.edu/~leechri/ORST/KalesVehiclePerformanceCalculator.xls


Finally, If anyone finds reliable information on a car which is not on the sheet and enters it into their own, could you post those stats in this thread, so that as I continually update the spreadsheet, I can keep adding more vehicles to it. Thanks, and enjoy. kale
 

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McLarens are V12, Ken Henderson's Supra is making well over 750hp, and there is probably some other stuff wrong in there. not being a dick, justs a heads up
 

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Member Thingy
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Discussion Starter · #3 ·
I'm well aware of the situation, and looking for errors all the time. The problem is finding reliable information from multiple sources, it makes for error. Post up any more you may find. Ken Henderson's car is on there on pump gas, crank horsepower, to match the rest of the crank HP figures. His score only drops with the 1000+ hp, as that power is virtually unuseable on a roadcourse.
 

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900 BHP Club :)
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nice work :)
 

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Member Thingy
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Discussion Starter · #6 ·
Sure, keep in mind anybody can add cars - just google their specs and insert them in an open space on the bottom, then press update. Or, change individual specs in whatever cell you like, for example, drop 100 lbs off a car, or add 100 hp - then hit update and it will all be recalculated. I'll see if I can find those porsche specs.
 

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Member Thingy
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Discussion Starter · #7 ·
List updated with the 2005 Porsche Carrera S, and fixed the cylinder count in the McLarens.
 

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Good work. However, I am curious on your equation, in particular, how the final score is derived. How do you weigh each variable? How did you measure powerband? What is the scale and is 100 the maximum score?

Also, why did you leave out some other vars such as gearing, drag coefficient, etc.?
 

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Member Thingy
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Discussion Starter · #9 · (Edited)
David S said:
Good work. However, I am curious on your equation, in particular, how the final score is derived. How do you weigh each variable? How did you measure powerband? What is the scale and is 100 the maximum score?

Also, why did you leave out some other vars such as gearing, drag coefficient, etc.?

The equation obviously takes all the variables present into account, and cross references each with about every other one. For example, to determine maximum potential for a vehicle to put power to the ground, I used tire size, aspect ratio, and width in comparison with the maximum torque figure and horsepower, in comparison with useable powerband derived from comparing displacement versus cylinders versus peak Hp and Tq versus redline etc. This defines a useable powerband, and that can be seen by plugging in 1000 hp for a car on skinny tires, or with a crappy powerband, and watching the rank not go up, in some cases drop. It gets pretty complicated, but is relatively crude versus some of the formulas which must run GT4 or Forza. The difference is that I only have available specs that can be found in any magazine, or readily found on the internet. I can't rely on dyno graphs to give me a true powerband or anything of the sort.

100 is not the maximum score. Technically, the scale is exponential, and not linear, though I built in a correction factor to account for this. For example, put in the specs for a shifter kart, and you'll see it almost hits 1000. You might think this is incorrect, but, it is where the weakness in the formula lies: Gearing, and stickyness of tire. If I could take gearing into account the equation would show the shifter kart has a top speed of about 120 mph, but then I have to ask, how can gearing be defined by a number?

The best solution I have come up with, was to take gear ratios and rev limit and determine top speeds in each gear. Even still though, what is defined as a "good" attribute of gearing? I have yet to answer this question, and until I can I have no way to implement it into the equation. I suppose, now that I am giving it a second thought, that you could figure out torque output to the ground across each gear and compare that to max engine torque output, and this would give you an idea of how efficiently the car is geared, then compare this to top speed in each gear, and overall top speed versus RPM. I'll have to think about it some more.

I do have a version of the equation which takes into account coefficient of drag and an equation which calculates downforce based on X downforce at Y RPM, which are the only stats I can seem to find. I decided to leave these attributes out because they only affected performance for the top set of cars, and even then the cars still remained in the same rank, since generally the higher performance the car, the better its aerodynamics will generally be. On top of this, I can't find data for all the rest of the normal cars, and so it would throw off the whole chart if I only include the specs for some.
 

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Member Thingy
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Discussion Starter · #10 ·
I almost missed the point of your question: I weighed the different attributres of the cars through a logical system which I thought best fit. I then went back and used trial and error to tweak the equation so that the output rank for each car matches the lap times of their real counterparts on several real life roadcourses. I used a series of benchmark cars, and after I was satisfied the equation worked, added in the rest. This is the only way I have been able to say that this formula is pretty close to accurate, for what data I have available to work with.
 

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Umm Ken's car is 50 something but a mclauren is 99. Ken's car has more HP, better 1/4, simialr other stats, but smaller tires...what's the deal here?
 

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Member Thingy
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Discussion Starter · #13 ·
Ken's car weighs more than 1000 lbs more than the McLaren, has a very unfriendly calculated powerband in comparison, and the Mclaren has a greater ability to put the power to the ground.

For the record, the reason Ken's Supra is in this comparison is because it is a great benchmark Supra, one which everybody knows and can identify in comparison, and finally, represents a great car from this community.
 
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